Dual-disc lapping machine



Nov. 24,1970 R. CLAR 3,541,734

DUAL-DISC LAPPING MACHINE Filed Feb. 27, 1968 5 Sheets-Sheet 1 IN V EN TOR.

Patented Nov. 24, 1970 3,541,734 DUAL-DISC LAPPING MACHINE Roland Clar, Schorndorf, Wurttemberg, Germany, as-

signor to Hahn & Kolb, Stuttgart, Germany Filed Feb. 27, 1968, Ser. No. 708,637 Claims priority, applicatiogr Germany, July 20, 1967,

6 ,329 Int. or. B24b /00, 7/00 US. Cl. 51-111 7 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION The invention refers to machine tools in general and to lapping machines for precision finishing of substantialy flat workpieces having two plane parallel faces.

Machines of this kind are known to have a workpiece holder for guiding the workpieces between the rotating upper and lower lapping disks whereby the two faces of the workpiece which are on opposite sides thereof, are precision finished. At the end of the working cycle the drive for the disks is switched off, the lower disk is stopped and the upper disk is lifted and swung outwardly so that the finished products can be taken out, and new pieces can be placed into the machine.

The problem exists in the conventional machines of this kind in that it cannot always be avoided that some of the finished workpieces, particularly those of light weight, may remain attached to the working face of the upper disk on the account of the adhesive effect of the lapping compound which preferably consists of abrasive powder suspended in oil or tallow, and are moved away from the workpiece holder. To remove them from the lifted and outwardly swung upper disk is a cumbersome and time consuming job. Furthermore some workpieces which adhere to the working face of the upper disk, may be overlooked since this working face is not directly in the viewing area of the operator. This can occur especially in the case of smal workpieces and it can cause considerable damage during the next following working cycle.

This aforementioned problem is solved by the present invention in a simple, efficient and quite effective manner.

SUMMARY The invention consists in such novel features, construction arrangements, combination of parts and improvements as may be shown and described in connection with the apparatus herein disclosed by way of example only and as illustrative of a preferred embodiment. Objects and advantages of the invention will be set forth in part hereinafter and in part will be obvious herefrom or may be learned by practicing the invention, the same being realized and attained by means of the instrumentalities and combinations pointed out in the appended claims.

The nature and gist of the inventive concept consists in creating a difference of the deceleration between the upper disk and the lower disk when the machine is switched 01f after an operating cycle has been accomplished. The lower rate of slowing down of the upper disk causes it to run a few seconds longer than the lower disk. By this mode of operation the film of the lapping compound which adheres to the working face of the upper disk and to the workpieces is wiped 01f whereby the workpieces are prevented from adhering to the upper disk when it is lifted off and is swung outwardly. Wiping of the lapping compound is further facilitated by compensating the weight of the upper disk during the deceleration period so that it is only pressed with a small force on the workpieces.

It is a general object of this invention to provide means for slowing down the upper disk of the dual-disk lapping machine at a lower rate than the lower disk when the machine is switched off.

Furthermore, it is an object of the invention to provide means for compensating of the weight of the upper disk during the slow-down period.

Another object of the invention is to provide means for preventing the workpieces from adhering to the upper lapping disk when the machine is unloaded after a working cycle has been accomplished.

Still another object of the invention is to provide simple and failproof yet relatively inexpensive means for wiping the adhering lapping compound off the working face of the upper-disk of the lapping machine when the machine is switched off.

Various further and more specific purposes, features and advantages will clearly appear from the detailed description given below taken in connection with the accompanying drawing which forms part of this specification and illustrates merely by way of example certain embodiments of the device of the invention.

BRIEF DESCRIPTION OF THE DRAWING In the following description and in the claims, parts will be identified by specific names for convenience, but such names are intended to be as generic in their application to similar parts as the art will permit. 'Like reference characters denote like parts in the several figures of the drawing, in which:

FIG. 1 shows a vertical section of the dual-disk lapping machine having two drive motors for the two lapping disks; and

FIG. 2 shows a vertical section of the dual-disk lapping machine having one single drive motor for both lapping disks; and

FIG. 3 shows the electric circuit diagram of the drive of the machine.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now in more detail to the drawing illustrating preferred embodiments by which the invention may be realized, there is shown in FIG. 1 a dual-disk lapping machine which has a lower stationary housing 11 and an upper, horizontally swingable housing 12, which is supported by an upper bearing 13 and a lower bearing 14. A lapping disk 15 is mounted on a vertical hollow shaft 16 which is rotatably supported by an axial bearing 17 and by radial bushings 18 and 19 in a gear box 20. A vertical shaft 21 is journalled in hollow shaft 16 by bushings 22, 23. Shaft 21 has on its upper end 24 a crank pin 25, which engages a workpiece holder 26 for movably holding workpieces 27 on top of disk '15.

A further vertical shaft 28 is arranged in gear box 20. Shaft 28 has two gears 29 and 30 mounted thereon, which mesh with gears 31 and 32, respectively. Gear 31 is mounted on hollow shaft '16, whereas gear 32 is mounted on vertical shaft 21. Shaft 28 furthermore has a pulley 33 on the free end thereof outside of gear box 20'. An electric motor 34 is attached to the wall of housing 11 and has a pulley 35. An intermediate short shaft 36 is arranged in housing 11, having an upper pulley 37 and a lower pulley 38. Thus, electric motor 34 drives by way of pulleys 35, 37 and belts 39 and by pulleys 38, 33 and belts 40 the lower lapping disk 15 and workpiece holder 26. Since the gear ratios of gears 29, 31 and of gears 30, 32 are different from one another, workpiece holder 26 rotates at a different speed than disk 15.

The upper lapping disk 41 is attached by way of a hub 42 to a vertical shaft 43, which is rotatably held in a cartridge 44. An hydraulic fluid cylinder is mounted in upper housing 12. Cartridge 44 has a ring 46 which is fitted in cylinder 45 like a piston. Hydraulic fluid under pressure can be admitted to cylinder 45 either on top or below ring 46 for applying pressure to lapping disk 41.

during the operating cycle or for compensating the weight of lapping disk 41 and the entire shaft assembly during the deceleration phase of disk 41 and for eventually lifting disk 41 off workpieces 27 when the machine is stopped for unloading and reloading of workpieces. The upper end 47 of shaft 43 is splined so that it may freely slide vertically through the correspondingly splined bore of a drive pulley 48 on shaft end 47, which is rotatably mounted on housing 12, coaxially with shaft 43. Pulley 48 hydraulic fluid under pressure is admitted through pipe is driven by the belts 49 and a pulley 50 which is attached at the upper end of a vertical shaft 51. Another pulley 52 is fixedly mounted at the lower end of shaft 51, which is driven by the electric motor 53 by way of the belts 54 and the motor pulley 55.

The lapping machine may be .driven by only one line 78 to hydraulic cylinder 45 whereby the weight of lapping disk 41 and of the entire shaft assembly is almost entirely compensated so that disk 41 is only pressed against workpieces 27 with very much reduced force during the final running time, whereby the lapping compound which adheres to workpieces '27 is wiped off.

When the drive of the'machine is arranged according to FIG. 2 electromagnetic coupling 58 is de-energized instead of motor 34 for stopping of lapping disk 15. Time delay relay 75 is correspondingly energized for keeping motor 53 running for a preset time which now is the only drive motor of the machine.

While the invention has been described and illustrated with respect to certain preferred examples which give satisfactory results, it will be understood by those skilled in the art after understanding the principle of the inventtion, that various other changes and modfications may be made without departing from the spirit and scope of the invention and it is intended therefore in the appended claims to cover all such changes and modifications.

What I claim is:

1. Lapping machine comprising two motor-driven lapping disks, said disks vertically arranged above one another, the upper one of said disks having means for being lifted and laterally swung out, a workpiece holder between said two lapping disks, said upper one of said disks comprising a time delay relay in said motor drive thereof, said relay permitting said upper one of said disks to keep running for a preset time after said lower one of said disks is stopped when said machine has been switched off.

2. Lapping machine according to claim 1, said drive motor of said upper one of said disks having a contactor and said time delay relay being connected with said contactor, said relay retarding the stopping of said drive motor of said upper one of said disks when said machine shafts 51 and 62 and stops shaft 62 by brakng it on stationary part 59. Motor 53 remains drivingly connected with shaft 51 driving upper lapping disk 41.

In order to keep upper lapping disk 41 rotating for a short time after the drive of lower disk '15 has been switched off, a time delay relay is arranged in the electric circuit which is shown in FIG. 3 for the machine shown in FIG. 1.

When selector switch 65 is closed, contactor 66 is closed. Thereby voltage is applied to contactor 67 of motor 34. The relays 68 and 69 will now close so that contactor 70 of motor 53 will close. At the same time the 68 and 6.9 also drop off. Thereby motor 34 is switched off and lower lapping disk 15 is stopped. At the same time, however, the delay contact 74 is closed whereby the time delay relay 75 starts running which has been set for the desired time of continuous running of motor 53 after motor 34 has been switched off, thus, motor 53 and upper lapping disk 41 keeps running until the preset time of delay relay 75 elapses. Then a contact 76 is opened whereby contactor 70 and time delay relay 71 are opened, so that motor 53 is stopped. Simultaneously delay contact 73 is closed and delay contact 74 is re-opened. This causes time delay relay 75 to be de-energized and contact 76 is closed again. By this operation the original starting condition is reset and a new working cycle can be started.

When time delay relay 75 is switched on, a solenoid -valve 77 can be opened (FIGS. 1 and 2), by which has been switched off.

'3. Lapping machine comprising one upper and one lower lapping disk drive means for said two lapping disks and a single motor for said drive means, said drive means comprising an electromagnetic coupling and a time delay relay, said coupling disconnecting said lower disk from said drive means, stopping said lower disk and activating said time-delay relay, said relay arranged for switching off said motor after said delaying time has expired.

4. Lapping machine according to claim 1, and switch means activating said lifting means when said lower one of said disks is stopped, said lifting means arranged for compensating the weight of said upper one of said disks while said upper disk is still running.

5. Lapping machines according to claim 3, and switch means activating said lifting means when said lower disk is disconnected and stopped, said lifting means arranged for compensatingthe weight of said upper disk while said upper disk is still running.

6. Lapping machine according to claim 4, said switch means comprising a solenoid valve for admitting hydraulic fluid to said lifting means.

.7. Lapping machine according to claim 5, said switch means comprising a solenoid valve for admitting hydraulic fluid to said lifting means.

References Cited UNITED STATES PATENTS 3,000,148 9/1961 Bovensiepen 51-111 2,975,563 3/1961 Bovensiepen 511l1 2,085,005 6/1937 Cole 51118 HAROLD D. WHITEHEAD, Primary Examiner 

